Diaphan ia indica (Saunders)is amajor LepidopteranpestofCucurbits. Some aspects of the biology and natural enemiesofthis pest on snalre gourd were studied. Larvae of D. indica collected from snake gourd vines were reared in the laboratory. Females laid eggs two days after copulation. The average fecundity was observed to be 267 eggs. The incubation period a t room temperature was 3-5 days. The larval period was 8-10 days and pupal period 7-9days. Themaximum longevity of the adult moth was 9 days.Two species of Braconid endoparasites (E1asn~u.s indicus and Apanteles taragamne) and an unidentified Ichneumonid ectoparasite were fbund to parasitize larvae of D.irzdica in the field. Due to the high level of parasitism by Elasn~us indicus (58.5%),the damage by D. indica to snalre gourd was not severe during the study period.

The short‐lived adult wheat midge Sitodiplosis mosellana deposits eggs on the seed head of various grasses close to the developing seeds on which larvae feed. The time taken to make egg‐laying decisions is investigated using three types of wheat Triticum aestivum seed heads. Young Roblin, Old Roblin and Young Key differ in their effects on ovipositing females (72%, 22% and 6% of eggs in choice tests, respectively) and effects on feeding larvae (75%, 25% and 5% larval survival, respectively). Within seconds of arriving, the female is able to distinguish Young Roblin from the two lower‐ranked types. However, the lower‐ranked types are not rejected at this time. Instead, all head types are examined before the female eventually flies away. On Young Roblin, probing with the ovipositor is the first behaviour that occurs. Thereafter probing and insertion of the ovipositor occupy most of the female’s time and behavioural transitions tend to be ‘progressive’, signalling a shift from low to high intensity examining. Differences between females visiting Old Roblin and Young Key are significant but take longer to emerge. On both, sitting is the first behaviour but, over the next 5–10 min, the female on Young Key exhibits more sitting, walking and ‘regressive’ transitions than the female on Old Roblin. It is suggested that, when the ovipositing female is short‐lived and incapable of controlled flight in all but essentially windless conditions, her behaviour is designed to thoroughly, rather than rapidly, examine a suboptimal host before abandoning it for the uncertain future of finding a better host.

The discovery of Sm1 , a highly effective resistance ( R ) gene that targets the first instar of the orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), has created concerns about wheat midge adaptation. Strategies for delaying adaptation to Sm1 include the simultaneous deployment of a resistance trait targeting a different life stage, i.e., the ovipositing adult female. Previous studies have shown that adult females distinguish between wheat genotypes and seed head developmental stages and are attracted by volatiles from young wheat heads. We focused on what happens after the female lands on the seed head, comparing in three tests a seed head of the high-ranked pre-anthesis 'Roblin' wheat, Triticum aestivum L. (Poaceae), and a head of one of three lower-ranked types: post-anthesis 'Roblin' , pre-anthesis 'Key' wheat ( T. aestivum ), and pre-anthesis 'Robust' barley ( Hordeum vulgare L.). Within each test, high-and low-ranked heads were presented in choice and no-choice assays, with the behavior of wheat midge females scored every 5 min from 20:30 to 23:00 hours, under mid-summer natural light conditions and sunset occurring between 20:50 and 21:20 hours. Head type influenced both proportions of females observed on the head and proportions of females probing with the ovipositor. Head*assay interactions occurred only in the test comparing wheat to barley, with barley reducing females observed on the wheat head and wheat increasing females probing on barley. Results indicate that the wheat midge female detects plant cues while examining the seed head and that this detection contributes to differences in egg counts.

Neotephritisfinalis (Loew) (Diptera: Tephritidae), and sunflower bud moth, Suleima helianthana (Riley) (Lepidoptera: Tortricidae) are major head-infesting insect pests of cultivated sunflower (Helianthus annuus L.). Planting date was evaluated as a cultural pest management strategy for control of N. finalis and S. helianthana in several production regions of North Dakota during 2009 and 2010. Results of the nine site-year study revealed that late planting date (early to mid-June) reduced damage ratings and percentage of damaged heads for N. finalis compared with early planting dates (mid- to late May). Visual observations of adult N. finalis found that the majority of flies were found in the early planted sunflower (78.2%) compared with the late planted sunflower (21.8%). Late planting date also reduced the percentage of S. helianthana damaged heads compared with early planting dates. Yield losses were reduced with late planting date when populations of N. finalis and S. helianthana were high enough to cause damage. Results of this study showed that delayed planting is an effective integrated pest management strategy that can reduce head damage caused by N. finalis and S. helianthana and mitigate yield losses.

For animals that lay eggs, a longstanding question is, why do females choose particular oviposition sites? For insects that lay eggs on plants there are three hypotheses: maximizing suitable habitat for juveniles, maximizing female lifespan, and maximizing egg survival. We investigated the function of the oviposition-site choice behavior of a gall midge, the Hessian fly, Mayetiola destructor (Say). In spite of living less than a day and having hundreds of eggs, the ovipositing female is choosy about the placement of eggs. Choosiness makes sense. The tiny gall-making neonate larva has limited movement and strict requirements for colonization. We examined whether offspring benefit from the Hessian fly female's preference for the plant's youngest leaf. To do this we restricted the female's access to the first, second, or third leaf of a seedling (wheat Triticum aestivum L.) plant. Being placed on older leaves did not impact egg survival or larval survival during migration to attack sites at the base of the plant, but did have negative impacts on egg-to-adult survival (reduced by 48%) and reproductive potential (reduced by 30-45%). These negative impacts appear to come from larvae having to search harder to find the limited number of reactive plant cells that can be reprogrammed to form the gall nutritive tissue. We propose that the ability of larvae to find these reactive cells in spite of being placed on an older leaf is important because it creates leeway for female behavior to evolve in the face of other selection pressures, e.g., attack by egg parasitoids.

Mosquito species Aedes aegypti and Aedes albopictus are vectors of dengue worldwide. Mosquito vector control through maintaining larvivorous fish in water bodies is generally suggested, however, its underlying role towards oviposition preference of these dengue vectors is unknown in the Sri Lankan context. The current study investigated the effect of chemical exudates from larvivorous fish species Poecilia reticulata, Rasbora daniconius and Applocheilus dayi on the oviposition preference of Aedes mosquitoes. The number of eggs laid by each mosquito species was determined using ovitraps that contained water conditioned by the fish species both separately and in combination. The ovitraps were placed inside insect cages containing engorged gravid Aedes females. Both the mosquito species had the least preference of oviposition in water conditioned by A. dayi followed by R. daniconius. The highest preference of oviposition was shown for water conditioned by P. reticulata. The current study indicated that oviposition site selection in Ae. aegypti and Ae. albopictus was reduced by A. dayi and R. daniconius, however, it was not influenced by the fish combinations used. Further studies are warranted to understand the chemical cues associated with larvivorous fish towards the oviposition preference in Aedes mosquitoes.

Background. Aedes aegypti is a major vector of arboviruses that may be controlled on an area-wide basis, using novel approaches such as Sterile Insect Technique (SIT) and Incompatible Insect Technique (IIT). Larval diet is a critical factor to be considered in mass rearing of Aedes mosquitoes for SIT and IIT programs. Therefore, the current study is aimed at evaluating the effects of two novel diets developed from dry fish powder on the growth and development of immature stages and adult fitness-related characteristics of Ae. aegypti in Sri Lanka. Method. Three batches of the first instar Ae. aegypti larva, each containing 250 larvae, were exposed to three different larval diets as standard dry fish powder (D1), dry fish powder meal and brewer’s yeast (D2), and International Atomic Energy Agency- (IAEA-) recommended diet (D3), separately. Morphometric and developmental parameters of the 4th instar larvae, pupae, and adult mosquitoes reared under different dietary treatments were measured. The entire experimental setup was replicated thrice. A General Linear Model (GLM) in the form of two-way ANOVA was used for the statistical analysis. Results. Significant diet-based variations were observed in the head length, head width, thoracic length, thoracic width, abdominal length, abdominal width, and total length ( F 2 , 87 > 4.811 ; P < 0.05 ) of Ae. aegypti larvae. The highest pupation success and the larval size were observed from the larvae fed the D2 diet, while the lowest was reported from D1. All adult morphometric parameters of adult male and female Ae. aegypti mosquitoes also denoted significant dietary variations, reporting the best-sized adults from the D2 diet ( F 2 , 87 > 3.54 ; P < 0.05 ). Further, significantly higher fecundity and male longevity were also shown by the adult Ae. aegypti ( F 2 , 6 > 7.897 ; P < 0.01 ) mosquitoes reared under diet D2. Conclusion. Based on all the growth and developmental parameters, the D2 diet tends to perform similar to the IAEA-recommended diet in mass rearing of Ae. aegypti mosquitoes, while being more inexpensive. Therefore, larval diet D2 could be suggested as the ideal diet for mass rearing of Ae. aegypti for IIT and SIT-based vector control in Sri Lanka.

Aedes albopictus is an important vector of dengue worldwide. Eliminating dengue in Sri Lanka depends entirely on controlling the vector and human-vectorhuman–vector contact. Thus, studying the bionomics and behavior of Ae. albopictus is paramount. The objective of this study was to evaluate the effect of the excreta of cow, goat and pig on the attraction, oviposition and development of Ae. albopictus. Bioassay chambers determined the mosquito stimulatory response. Ovitraps determined Ae. albopictus oviposition preference to excreta singly, in combination and on fermentation. The excreta effect on larval development was also determined. The results revealed that Ae. albopictus gravid females were significantly attracted to goat excreta but were repelled by pig excreta. The oviposition preference was highest for cow excreta and lowest for pig excreta. For excreta combinations, the Cow+Goat combination increased the oviposition while the Pig+Goat combination reduced the oviposition. The oviposition preference of Ae. albopictus increased with the rate of fermentation. The pig excreta increased the Ae. albopictus larval mortality, larval and pupal duration and reduced adult fecundity, whereas the cow excreta positively affected all these aspects. Our findings additionally suggest that a high abundance of Ae. albopictus in rural areas of Sri Lanka may be due to its oviposition attraction and growth performance for vertebrate excreta.